The present invention relates to electrical power distribution systems. More specifically, the present invention relates to a method and apparatus for injecting harmonic currents into constant frequency and variable frequency distribution systems.
Many aircraft include power distribution systems for supplying ac power to loads such as ac-to-dc converters, ac-to-ac converters, on-board electronics, and electromechanical/electrohydrostatic actuators. Many of these loads contain non-linear devices such as bridge rectifiers and inverters.
The non-linear devices can create harmonic currents on the system's power distribution line. The harmonic currents can disrupt other loads connected to system's main power supply (e.g., electrical generators, inverters) and cause malfunction, and even failure, of the other loads.
It would be desirable to remove the harmonic currents without cutting into the power distribution line and measuring main distribution current. In aircraft power distribution systems, the main distribution current can be quite large. For example, a 115/208 volt, three-phase 150 KVA generator has a rated current of approximately 450 amperes.